Small is beautiful mate, frosty as fuck so as you say, that's why your doing all this.... for the quality!!! They are some tasty looking buds there!
I can't help wondering why they stayed so short, by day 20 they should have been a bit bigger.... I had this issue with soil, which is why I switched to Coco, but have you thought of adding some kind of root stimulator in the early weeks (weeks 2-onwards), (like H&G Roots excellurator), and maybe an enzyme to breakdown dead root into absorbable micronutrient?
Were you doing circumferential watering in weeks 1-3 to encourage root scavenging? And what was your light height, i found that I got taller plants by pissing around with the heights, 3ft was good for me to start with, I didnt adj the height of the lights, the plants grew up to them. Once they got established, they liked the lights a bit closer. Autos need the best possible start and a good 1st 4 weeks to get the best out of them.
Something was slowing them down mate, I reckon once you nail that, you will be asking for a chainsaw recommendation!
Are you using any bloom boosters..... PK13/14 or anything?
You might also wanna look at the Tropf Blumat watering system, very reliable, and reasonably cheap. Glad you beat the bug!